Computer Science
Scientific paper
Sep 1993
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993e%26psl.119..319p&link_type=abstract
Earth and Planetary Science Letters (ISSN 0012-821X), vol. 119, no. 3, p. 319-329
Computer Science
25
Basalt, Earth Mantle, Helium Isotopes, Ocean Dynamics, Oceanography, Plumes, Tectonics, Volcanoes, Anomalies, Chemical Composition, Geochemistry, Mid-Ocean Ridges, Pacific Ocean
Scientific paper
He-3/He-4 ratios in Easter Microplate basalt glasses show clear evidence of the effects of a mantle plume. The East Rift of the microplate between 26 and 28 deg S, identified by La/Sm, Sr and Pb isotopes and ridge crest elevation as the region of maximum plume influence, has He-3/He-4 ratios spanning the entire range from 7.5 to 11.7 R(sub A). The Easter Microplate is the only section of the entire East Pacific Rise that is associated with a known `hotspot' track (mantle plume) and has elevated He-3/He-4 ratios. Although most of the West Rift basalts contain MORB helium (8.0 - 8.7 (R sub A)), the basalt closest to the East Rift has an elevated He-3/He-4 ratio (11.3 R(sub A)), consistent with a significant plume component. The diversity in isotopic signatures also indicates that homogenization of isotopic anomalies does not occur, even in this region of `super-fast' spreading. The overall He-3/He-4-Pb-206/Pb-204 and He-3/He-4-Sr-87/Sr-86 trends have positive correlations, although the high between the He and Sr isotope distribution is modeled in the context of a plume source-migrating ridge sink. During channeling of the plume toward the ridge, helium if preferentially lost from the center of the channeled plume, resulting in lower He/Pb and He/Sr concentration ratios in the high He-3/He-4 component. Mixing trajectories in He-Sr isotopic space between a LILE depleted asthenosphere and a variably degassed plume component provide a reasonably good fit to the data and may explain the isotope systematics of plume-ridge interactions in the context of modern theories of plume dynamics.
Craig Harmon
Poreda Robert J.
Schilling Jean-Guy
No associations
LandOfFree
Helium isotope ratios in Easter microplate basalts does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Helium isotope ratios in Easter microplate basalts, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Helium isotope ratios in Easter microplate basalts will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1562216